Apparatus for automatically dispensing flowable mediums are employed in a wide range of settings, ranging from kitchens to industrial facilities. Thus, a general purpose apparatus must be able to dispense a wide range of flowable mediums, including liquids, semi-liquids and liquids containing particulate matter. Preferably, the flowable medium should be dispensed automatically in a continuous, regulated stream.
A soup dispenser is a typical dispensing apparatus. In recent times, salad bars have gained in popularity in restaurants and fast-food chains due to the increasing number of health-conscious patrons who count their calories. Soup, laden with chunks of meat and vegetables, is a wholesome, nutritious item that is served in virtually every salad bar. To allow the patrons to help themselves, the soup is served from a soup dispenser.
One known type of soup dispenser includes a reservoir of soup that is gravity fed into a receptacle, such as a cup or bowl. The soup is discharged through an orifice in the reservoir and regulated by a valve. The discharge or flow rate in these gravity-feed systems is dependent upon the height of the soup (i.e., the "head") in the reservoir. This dependency causes problems in dispensing the soup. That is, because the height of the soup in the reservoir varies as the soup is dispensed, the rate of discharge also varies. As the height of the soup decreases, the resulting head pressure decreases which, in turn, decreases the rate of discharge. Thus, the soup is discharged at a continually decreasing rate, thereby making it difficult to dispense any one specific incremental amount with any degree of certainty. This head problem also causes an undesirable splattering effect, especially when high head pressures result in the soup being discharged very rapidly. Such splattering and sudden dumping resulting from high head pressures do not subside until the reservoir is partially emptied.
Many conventional soup dispensers have eliminated the head problem described above. The most basic of these conventional soup dispensers is a cauldron and ladle with the soup being withdrawn from the cauldron by the ladle. Although the soup is dispensed in premeasured portions without splattering, it is not dispensed automatically or in a continuous stream.
Improvements have been made to gravity-feed soup dispensers in the manner of dispensing premeasured amounts of soup by automatic means. For example, U.S. Pat. No. 4,032,045 discloses a soup dispenser having a volumetric trap valve journalled for rotation for removing soup in premeasured amounts from a reservoir. As the valve is aligned with an opening in the reservoir, soup flows into the trap. As the valve is further rotated, the soup is dispensed from the trap. Other similar soup dispensers are disclosed in U.S. Pat. Nos. 4,174,789; 4,176,766; 4,189,071; and 4,361,176, each of which operates to dispense a premeasured quantity of soup by selectively dispensing the soup into containers located within the dispenser and then emptying the contents of the selected containers into a receptacle. Although this type of dispenser has effectively eliminated irregular discharge caused by the head problem, such dispensers cannot provide a continuous discharge of the soup.
A number of additional problems are inherent with the conventional apparatus for dispensing soup. For example, sanitary problems abound because the cauldrons and reservoirs of many soup dispensers are open, thereby allowing dirt and other foreign matter to fall in. Cauldrons are also especially unsanitary in a communal setting when ladles contact other surfaces and are then placed therein.
Another problem arises from the method of heating the soup. The typical soup dispenser includes a heating element placed under the base of an open-faced reservoir. Since the heating element and hot base are exposed to the user, this arrangement is hazardous. Such open-faced reservoirs also loose heat through their open-faces. To compensate for the resulting heat loss, additional heat must be added. Not only does this waste energy, but it also has the unwanted effect of burning soup in the reservoir and evaporating the soup therein. When the soup is allowed to evaporate, water must be constantly added to the reservoir for the purpose of diluting the remaining soup.